This study tests a congruence model of mental health for older adults based on that of French, Rodgers and Cobb, upon the most vulnerable and fastest growing segment of the population, old women living alone. Mental health is hypothesized to depend both upon personal competence and environmental press (Lawton), and upon environmental "fit" with personal needs (Kahana). Characteristics of environments (social and physical) and persons are measured at objective and subjective levels. Congruence terms are derived through scaling rather than by pre-classification or use of a difference score. Mental health is indexed by maladaptive behavior, life satisfaction, depression and happiness, and by individual differences in behavior, rather than either activity or disengagement. Multiple regression analysis is used in hypothesis testing.